FIG. 1 is an exemplary view illustrating a related art terminal having a battery, wherein the terminal 10 is directly connected with a battery 20 without any device that checks conditions of the battery 20. The battery 20 has a protective circuit therein to protect generally against an overcharge, overdischarge and a short circuit. In case of overcharge and overdischarge, the protective circuit detects a voltage of the battery 20 and compares the detected voltage with a reference voltage using a comparator. If the detected voltage of the battery 20 is more or less than the reference voltage, the protective circuit may disconnect the battery power from the terminal circuitry. Also, if a current flowing in an internal resistor inside the battery 20 is greater than a reference current, the protective circuit recognizes the battery 20 as having a short circuit, and also disconnects the battery power from the circuitry.
However, there is no sensor to detect an expansion of the battery 20 that may cause battery fluid to leak, or an abnormally high battery temperature. Because these conditions are not detected, the battery power continuously connected to the terminal circuitry potentially causing a dangerous situation such as an explosion thereby placing a user in danger.